Lamb　waves　are　used　to　detect　fouling　in　food　vessels.　The　propagation　of　the　Lamb　waves　in　plates　exhibits　many　modes　and　dispersion　characteristics,　which　have　great　influence　on　fouling　detection.　The　relative　distribution　of　the　in-plane　and　out-of-plane　displacement　of　the　mode　across　the　thickness　of　the　plate　will　determine　the　sensitivity　of　the　mode　to　a　particular　loading　condition.　By　considering　the　dispersion　and　multi-mode　characteristics　of　guided　waves,　an　interdigital　polyvinylidene　fluoride　(PVDF)　transducer　is　designed　to　realize　the　mode　selection　of　guided　waves,　and　a　single　a0　mode　is　used　for　guided　wave　detection.　Fouling　detection　experiments　are　conducted　in　the　laboratory　using　epoxy　adhesive　on　a　thin　plate.　Using　the　interdigital　PVDF　transducer,　three　fouled　areas　are　detected.　Using　one　of　the　time-frequency　analysis　methods,　the　waveforms　are　further　processed.　This　also　demonstrates　the　validity　of　this　method　of　fouling　detection.